海南岛西南海域古河道空间分布规律及地质意义

Spatial Distribution Laws and Geological Significances of Paleo-channels Under the Ocean of Southwestern Hainan Island

古河道是陆架出现最多的限制性灾害地质因素,分析其空间分布规律并挖掘隐藏其中的地质信息,能为海洋工程建设与防灾减灾提供科学依据,并有助于复原沉积作用的发育历史。从单道地震剖面识别古河道并对其空间分布规律进行分析后发现,海南岛西南海域沉积层中至少有3期埋藏古河道分布,其中30~80 m水深最为发育,推测分别发育于MIS2、MIS4及MIS5;古河流整体上沉积动力条件较弱,古河道空间分布总体上受海南岛岸线空间分布控制,沉积物主要来源于海南岛陆域,部分沉积物可能来源于古红河流域;即便受到海平面升降的影响,水系空间分布格局在时间上仍然具有较强的延续性。

Paleo-channels are one of the geological hazards on the continental shelf.Analyzing the laws of spatial distribution and unearthing the hidden geological significances could provide basis for ocean engineering and disaster prevention and mitigation,and it′s useful to restore the sedimentary processes.After paleo-channels were identified and their spatial distribution laws were studied,three periods were sorted for paleo-channels in the sedimentary layers under the ocean of southwestern Hainan Island,most of which were found under the seabed above which the depth is from 30 m to 80 m,which were speculated to be developed in MIS2,MIS4 and MIS5.The hydrodynamic forces of ancient rivers were weak on the whole,and the spatial distribution of paleo-channels were generally controlled by the spatial distribution of coastlines in Hainan Island.Most of the sedimentary materials were from Hainan Island,Some of which may come from the paleo Red River basin.Although affected by sea level fluctuation,the spatial distribution pattern of river system had strong continuity under the influence of sea level fluctuation.